Friday, April 22, 2016

In my last post, I gave a basic introduction to ethereum mining. Since there is not much information available about eth mining compared to bitcoin mining, and some of the information I have found is even wrong, I decided to go into more detail on eth mining.

Comparing the bitcoin protocol to ethereum, one of the significant differences is the concept of uncle blocks. When two miners find a block at almost the same time, only one of them can be the next block in the chain, and the other will be an uncle. They are equivalent to stale blocks in bitcoin, but unlike bitcoin where the stale blocks go unrewarded, uncle blocks are rewarded based on how "fresh" they are, with the highest reward being 4.375 eth. An example of this can be found in block 1,378,035. Each additional generation that passes (i.e. each increment of the block count) before an uncle block gets included reduces the reward by .625 eth. An example of an uncle that was 2 generations late getting included in the blockchain can be found in block 1,378,048. The miner including the uncle in their block gets a bonus of .15625 eth on top of the normal 5 eth block reward.

Based on the current trend, I expect the uncle rate to be in the 6-7% range over the next few months. With the average uncle reward being around 3.5 eth (most uncles are more than one generation old), uncles provide a bonus income to miners of about 4%. Since uncles do not factor into ethereum's difficulty formula, when more uncles are mined the difficulty does not increase. The mining calculators I've looked at don't factor in uncle rewards, so real-world returns from mining in an optimal setup should be slightly higher than the estimates of the mining calculators.

Another thing the calculators do not factor is the .15625 eth uncle inclusion reward, but this is rather insignificant, and most pools do not share the uncle inclusion reward. Assuming a 6% uncle rate, the uncle inclusion reward increases mining returns by less than 0.2%. If your pool is down or otherwise unavailable for 3 minutes of the day, that would be a 0.21% loss in mining rewards. So a stable pool with good network connections is more important than a pool that shares the uncle inclusion reward. Transaction fees are also another source of mining revenue, but most pools do not share them, and they amount to even less than the uncle inclusion reward in any case.

Finding a good pool for ethereum mining has been much more difficult than bitcoin, where it is pretty hard to beat Antpool. For optimal mining returns, you need to use stratum mode, and there are two main variations of the stratum protocol for eth mining; dwarf and coinotron. Coinotron's stratum protocol is directly supported by Genoil's ethminer, which avoids the need to run eth-proxy in addition to the miner. Coinmine.pl and miningpoolhub.com support coinotron's stratum protocol, while nanopool, f2pool, and mininpoolhub support dwarf's protocol. Miningpoolhub is able to support both on the same port since the json connection string is different.

Coinmine.pl and coinotron only have servers in Europe, and half the time I've tried to go to coinotron's web site it doesn't even load after 15 seconds. Miningpoolhub has servers in the US, Europe, and Asia, and has had reasonable uptimes. As well, the admin responds adequately to issues, and speaks functional english. They have a status page that shows enough information to be able to confirm that your mining connection to the pool is working properly. I have a concern over how the pool reports rejected shares, but the impact on mining returns does not appear to be material. Rejected shares happens on other pools too, and since I am still investigating what is happening with rejected shares, there is not much useful information I can provide about it.

Saturday, April 16, 2016

After bitcoin, ethereum (eth) has the highest market capitalization of any cryptocurrency. Unlike bitcoin, there are no plug-and-play mining options for ethereum. As was done in the early days of bitcoin, ethereum mining is done with GPUs (primarliy AMD) that are typically used for video gaming.

The first ethereum mining I did was with a AMD R9 280x card using the ethereum foundation's ethminer program under Windows 7e/64. The installer advised that I should use a previous version of AMD's Catalyst drivers, specifically 15.7.1. Although the AMD catalyst utilities show some information about the installed graphics card, I like GPU-z as it provides more details. After setting up the software and drivers, I started mining using dwarfpool since it was the largest ethereum mining pool.

As an "open" pool, dwarf does not require setting up an account in advance. One potential problem with that is the eth wallet address used for mining does not get validated. I found this out because I had accidentally used a bitcoin wallet address, and dwarfpool accepted it. After fixing it, I emailed the admin and had the account balance transferred to my eth wallet.

Dwarf recommends the use of their eth-proxy program, which proxies between the get-work protocol used by ethminer, and the more efficient stratum protocol which is also supported by dwarfpool. Even using eth-proxy, I wasn't earning as much ethereum as I expected.

The ethereum network is running the homestead release as of 2016/03/14, which replaced the beta release called frontier. The biggest change in homestead was the reduction in the average block time from 17 seconds to 14.5 seconds, moving half way to the ultimate target of a 12-second block time. I wasn't sure if the difference in the results I was getting from mining was due to the calculators not having been updated from frontier or some other reason. After reading a comment in the ethereum mining forum, I realized returns can be calculated with a bit of basic math.

The block reward in ethereum is 5 eth, and with an average block generation time of 14.5 seconds, there is 86400/14.5 * 5 = 29793 eth mined per day. Ethereum blockchain statistics sites like etherscan.io report the network hash rate which is currently around 2,000 gigahashes per second. A R9 280x card does about 20 megahashes per second, or 1/100,000th of the network hashrate, and therefore should earn about 29,793/100,000 or 0.298 eth per day. The manual calculations are in line with my favorite eth mining calculator (although it can be a bit slow loading at times). Due to the probabilistic nature of mining, returns will vary by 5-10% up or down each day, but in less than a week you can tell if your mining is working optimally.

Using the regular ethminer, or even using eth-proxy, I was unable to get pool returns in line with the calculations. However using Genoil's ethminer, which natively supports the stratum protocol, I have been able to get the expected earnings from ethereum.miningpoolhub.com. Dwarf uses an unsupported variation of the stratum protocol, so I could not use Genoil's ethminer with it. I briefly tried nanopool, but had periods where the pool stopped sending work for several minutes, even though the connection to the pool was still live.

Both the official ethminer and Genoil's version were built using MS Visual C++, so if your system doesn't already have it installed, you'll need MS Visual Studio redistributable files. Getting the right version of the AMD Windows catalyst drivers for ethminer to work and work well can be problematic. Version 15.12 works at almost the same speed as 15.7.1, however the crimson version 16 drivers perform about 20% slower.

For me, as a Linux user for over 20 years, the easiest setup for eth mining was with Linux/Ubuntu. I plan to do another post about mining on Ubuntu.

About Me

I have four children, two step-children, and a grand-daughter. Wife 1.0 was a failure, but as with many nerd projects, version 2.0 is a big improvement. :-) As an adult I was diagnosed with ADHD and Asperger's. gmail: ralphdoncaster